Amorphization of crystalline Si due to heavy and light ion irradiation

The formation of amorphous silicon in crystalline silicon by bombardment with light (Si) and heavy (Xe) ions has been investigated by transmission electron microscopy with in situ ion irradiation. Experiments have been carried out at room temperature and low temperature (50 K) and the results are compared to a simple numerical model for amorphization. The results indicate that the amorphization mechanisms for both irradiations are heterogeneous in nature and that numerous overlaps of the collision cascade are generally required to render the crystal amorphous. Following from this, the nature of the material within the confines of collision cascades will be discussed and it will be shown that the individual cascade volume is not necessarily amorphous as previously described in the scientific literature but contains varying degrees of damage depending on the energy deposited within the cascade. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3195081]